Effect of buffer composition on binding of adenosine 3′:5′-cyclic monophosphate by bovine adrenal extracts

Abstract
The binding of cyclic [3H]AMP by bovine adrenal extracts was studied in different buffer systems; 50 mM-Tris/HCl, pH 7.5, buffer containing 4 mM-EDTA (disodium salt) offered advantages such as low non-specific interference and high binding affinity. 2-Mercaptoethanol decreased, but EDTA and theophylline increased, the specificity of cyclic[c][3H]AMP binding as expressed by the displacement of c[3H]AMP by a 1000-fold excess of unlabeled cGMP. The study indicated heterogeneity of the binding material. Mg2+-dependent binding may be eliminated in Tris/EDTA buffer. The heterogeneity and the specificity of intracellular cAMP binders and their dependence in environmental factors should be considered in the evaluation of cAMP binding and 2nd-messenger systems.

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